Add rust-bundle, a single staticlib crate that depends on both libchat
and rln as rlibs. This ensures rustc links Rust std exactly once,
eliminating duplicate symbol errors on all platforms. Nim targets link
against liblogos_chat_bundle.a; Nix uses a bundleDrv instead of
separate libchat and rln derivations.
Reference: https://doc.rust-lang.org/reference/linkage.html#mixed-rust-and-foreign-codebases
* fix: mac build
- fix error: `error: darwin.apple_sdk_11_0 has been removed as it was a legacy compatibility stub`
- fix librln hash
- bumped nim-ffi
* fix: typo
